RFR: 8154787: gc/g1/Test2GbHeap.java fails with java.lang.RuntimeException

[Michail Chernov]

Hi,

Could I have a review for this small fix which excludes execution of 
test on 32-bit systems please.

https://bugs.openjdk.java.net/browse/JDK-8154787
http://cr.openjdk.java.net/~mchernov/8154787/webrev.00/

Testing was performed on different configurations.

Thanks
Michail